The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a hotspot-generated seamount chain; however, the lack of a predictable age progression has stymied previous models for the origin of this feature. We combined plate-tectonic reconstructions with seamount age dates and available geochemistry to develop a new model that involves multiple melt regions and multiple melt delivery styles to explain the spatial and temporal history of the Line Islands system. Our model identifies a new melt source region (Larson melt region at ~17°S, ~125°W) that contributed to the formation of the Line Islands, as well as the Mid-Pacific Mountains and possibly the Pukapuka Ridge.The Line Islands chain is a collection of seamounts and volcanic ridges located in the central Pacific Ocean with a general northwest-southeast trend along its 4500 km length (Fig. 1; Fig. S1 in the Supplemental Material1). The eruption age of the Line Islands generally falls between 88 and 50 Ma; however, there is no apparent age progression along the volcanic chain (Clague and Jarrard, 1973; Winterer, 1973; Jackson and Schlanger, 1976; Lanphere and Dalrymple, 1976a, 1976b; Schlanger et al., 1976; Saito and Ozima, 1977; Haggerty et al., 1982; Davis et al., 2002).Previous attempts to explain the origin of the Line Islands with a single hotspot trace (e.g., Morgan, 1972) were unable to account for the complex age distribution, so models with multiple hotspots were proposed (e.g., Crough and Jarrard, 1981; Duncan and Clague, 1985). Alternative models included leaky transform faults (e.g., Orwig and Kroenke, 1980; Farrar and Dixon, 1981) or tensional cracks in the lithosphere related to cooling of the plate or differential far-field stresses that provided pathways for sublithospheric melt to erupt on the seafloor (e.g., Natland and Winterer, 2005). A more recent interpretation also suggested that neither single nor multiple hotspot models can explain the origin of the Line Islands (Davis et al., 2002). Instead, the melting of a heterogeneous mantle in a region of diffuse lithospheric extension was thought to lead to the complex eruption history.We revisited the question of the origin of the Line Islands by developing a tectonic reconstruction of the Pacific plate from 130 Ma to present. Our model uses updated plate motion models (Matthews et al., 2016) and a compilation of age-dated seamounts (Clouard and Bonneville, 2005; Seamount Catalog Home Page, https://earthref.org/SC/ [accessed August 2019]) to constrain the spatial and temporal eruption history of the Line Islands system. We also reviewed isotope geochemistry data to verify that our interpretation is consistent with available information. Our study primarily represents a test of mantle plume models for the origin of the Line Islands system, but we acknowledge that some characteristics of this complex region are not readily explained solely by mantle plumes and may require alternative tectonic and magmatic processes.The morphology of the Line Islands volcanic chain varies dramatically along its length (Fig. 1A; Fig. S1). The northernmost region, which we term the Northern Volcanic Province, is a collection of individual seamounts and east-west–trending seamount chains distributed over a 900 × 1500 km region located immediately southeast of the Mid-Pacific Mountains, including Johnston Atoll. The central region of the chain is defined by the 1200-km-long and 200-km-wide volcanic Line Islands Ridge. The northern end of the Line Islands Ridge is a circular plateau that includes Kingman Reef and Palmyra Atoll, while the southern end includes Fanning and Christmas Islands. Continuing southward, the Boudeuse Ridge is a 1200-km-long linear chain of closely spaced seamounts that forms the southern segment of the Line Islands system. The age of volcanism along the length of the Line Islands system ranges from 91 to 24 Ma, with most of the dated seamounts (23 of 27) having ages between 86 and 55 Ma (Table S2) and no apparent age progression along the volcanic chain (Fig. 1B).Two additional volcanic features located at either end of the Line Islands are the Mid-Pacific Mountains to the northwest and the Pukapuka Ridge to the southeast (Fig. 1A; Fig. S1). The Mid-Pacific Mountains are a broad volcanic plateau extending over 2000 km, with a roughly east-west trend, southwest of the Hawaiian Ridge. The western half of the Mid-Pacific Mountains is roughly equidimensional in plan view (1200 × 1200 km) with age dates ranging from 128 to 88 Ma, while the eastern half is more elongate (800 × 150 km) and oriented in a southwest-northeast direction with a single eruption age date of ca. 73 Ma. At the easternmost end, there is a series of narrow ridges trending southwest-northeast that includes Necker Ridge with eruption ages ranging from 88 to 82 Ma. Pukapuka Ridge, at the southern end, is a series of discontinuous volcanic ridges with an east-west trend spanning a distance of 2500 km between the Tuamotu Islands (to the west) and the Rano Rahi seamounts (to the east). The volcanism along Pukapuka Ridge exhibits a general age-progressive trend from ca. 11 Ma at the western end to ca. 6 Ma at the eastern end near the East Pacific Rise (Sandwell et al., 1995).We used GPlates tectonic reconstruction software (Müller et al., 2016; https://www.gplates.org/) and included rotation poles (Matthews et al., 2016), hotspot locations on the Pacific plate (Table S1; Courtillot et al., 2003; Morgan and Morgan, 2007), and a compilation of dated seamounts in the central Pacific (Table S2; Clouard and Bonneville, 2005; Seamount Catalog Home Page) to model the volcanic evolution of the Line Islands (Figs. 1 and 2). We used a qualitative forward modeling approach with a series of trial-and-error hotspot locations to obtain a visual best-fit model.Our initial models displayed good temporal and spatial correlation of the Crough hotspot track with the Boudeuse Ridge, the Tuamotu Islands, and possibly the southern end of the Line Islands (Fig. 1B). However, the Northern Volcanic Province and northern half of the Line Islands Ridge were not well predicted by the Crough hotspot track, and while they are closest to the Marquesas hotspot track, they are still far away (~500 km). Furthermore, this initial reconstruction did not account for the mixture of seamount ages along the Line Islands Ridge and the Northern Volcanic Province.Our preferred reconstruction requires an additional melt source region currently located along an arc between 16°S, 129°W and 22°S, 124°W (Fig. 1C), which we call the Larson melt region, in memory of Roger Larson's significant contributions toward unraveling the complex tectonic history of the Pacific Basin (Pockalny et al., 2015; Fletcher et al., 2020). This new hotspot is located between the Crough and Marquesas hotspots near the eastern limit of the Pukapuka Ridge. The tectonic reconstruction traces a path along the Line Islands Ridge, through the heart of the Northern Volcanic Province, and along the Mid-Pacific Mountains (see Videos S1–S4 in the Supplemental Material).The spatial and temporal history of the Larson melt region is coincident with much of the volcanism along the Line Islands system, and also the adjacent Mid-Pacific Mountains and Pukapuka Ridge (Figs. 1C, 2, and 3). The Crough hotspot appears to coincide with the southern end of the Line Islands, while the Marquesas and Tahiti hotspots potentially may coincide with portions of the northern end of the Line Islands but to a much-reduced extent (Fig. 1B).In our proposed scenario (Figs. 2 and 3), the western Mid-Pacific Mountains were formed 130–110 Ma through a plume-ridge interaction with the Larson melt region. The melt region at this time was likely a robust melt event (i.e., plume head) located within 500 km of the Pacific-Farallon spreading axis (e.g., Thiede et al., 1981; Fletcher et al., 2020). The eastern portion of the Mid-Pacific Mountains appears to be younger than the western portion and overlays an inferred trace of a precursor of the Molokai Fracture Zone. A later stage of distributed volcanism on the Mid-Pacific Mountains may have been due to the passage of the Tahiti hotspot from 110 to 85 Ma.Necker Ridge and related northeast-trending narrow volcanic ridges at the eastern end of the Mid-Pacific Mountains (Figs. 1–3; Fig. S1) may be the result of an off-axis extensional eruption event that coincided with the Larson melt region at ca. 95 Ma or with the Marquesas hotspot at 85–75 Ma.According to our model, the Line Islands proper are likely the combined result of the Larson, Crough, and Marquesas hotspots (Figs. 2 and 3). The Northern Volcanic Province appears to have been caused by distributed volcanism associated with the Larson melt region from 100 to 75 Ma and possibly the Marquesas hotspot from 75 to 65 Ma. The northern half of the Line Islands Ridge coincides with the passage of the Larson melt region from 80 to 65 Ma, while the southern half coincides with the Crough hotspot from 100 to 85 Ma and the Larson melt region from 70 to 50 Ma. The cross-grain ridges emanating from the eastern side of the Line Islands Ridge suggest an extensional environment (Davis et al., 2002), but we interpret the similar trends of the hotspot tracks and the Line Islands as a melt conduit hotspot track (e.g., Morgan, 1972). The track of the Crough hotspot coincides with the Boudeuse Ridge from 75 to 45 Ma and also suggests a melt conduit melt delivery style.Beyond the southern end of the Line Islands, the Crough hotspot coincides with the Tuamotu Islands from 50 to 20 Ma and parallels the series of seamounts connecting the Tuamotu Islands with the Easter microplate (Figs. 2 and 3). Limited seamount age information does not provide enough information to assess the melt delivery style, so these features may be due to either melt conduits or lithosphere extension. The Pukapuka Ridge, however, is likely the result of lithosphere extension, with the Larson melt region as a possible melt source (Sandwell et al., 1995; Lynch, 1999; Janney et al., 2000).We propose four different melt sources (e.g., Crough, Marquesas, Tahiti, and Larson hotspots) to explain the formation of the Line Islands and adjacent Mid-Pacific Mountains and Pukapuka Ridge (Figs. 2 and 3; Fig. S2). The Larson and Crough hotspots were the predominant contributors to the volcanism, but neither of these melt sources is consistently listed in catalogs of deep mantle plumes or hotspots (e.g., Courtillot et al., 2003; Montelli et al., 2006). Shear-wave velocity models (French and Romanowicz, 2015), however, suggest that both of these hotspots may have been associated with mantle plume sources (Fig. 4). The Larson and nearby Pitcairn hotspots are linked to a deep-mantle plume source in the broad South Pacific superswell region. The Crough and possibly the Easter hotspots are associated with a midmantle plume source near the Easter microplate. The Marquesas hotspot also appears to be connected to a midmantle plume source, while the Tahiti hotspot appears to have a shallow mantle source, based on the shear-wave velocity models.Several melt delivery processes are proposed to explain the various volcanic morphologies observed along the Line Islands system (Fig. 3). Our proposed plume-ridge origin of the Mid-Pacific Mountains, the melt conduit origin of the Boudeuse Ridge, and the lithosphere extension origin of the Pukapuka Ridge are consistent with previous explanations (Winterer and Metzler, 1984; Lynch, 1999; Davis et al., 2002). The melt delivery style of the Line Islands Ridge was most recently attributed to diffuse lithospheric extension and subsequent volcanism (Davis et al., 2002); however, the large erupted volumes and the orthogonal orientation of the volcanic chain relative to the intersecting fracture zones are significantly different from other proposed extensional volcanic ridges (e.g., Pukapuka Ridge). We believe the spatial and temporal history of the Line Islands Ridge is better explained by overlapping conventional hotspot tracks of the Crough hotspot and Larson melt region. The Northern Volcanic Province was also previously attributed to lithosphere extension to explain the cross-grain seamount chains (e.g., Keli Ridge) in the region (Natland, 1976). We believe this mechanism is still a viable origin, but we also suggest a distributed volcanism origin to explain the dispersed seamounts. In our interpretation, the melt source for the distributed volcanism of cross-grain seamounts would be small, residual mantle heterogeneities related to the passage of the Larson melt region and/or Marquesas hotspots.Limited geochemical data from seamounts and ridges along the Line Islands system and related volcanic features provide additional constraints and clues for their possible origins (Fig. S2; Table S3). This is best shown in the plot of 87Sr/86Sr versus 206Pb/204Pb, where the majority of samples from the Northern Volcanic Province and northern section of the Line Islands Ridge (yellow triangles) (Garcia et al., 1993; Konter et al., 2008) cluster together and are coincident with the samples from the Boudeuse Ridge (blue inverted triangles) (Garcia et al., 1993), one sample from Necker Ridge (yellow diamond) (Garcia et al., 1993), and a sample at the western end of the Pukapuka Ridge (yellow star) (Janney et al., 2000). This clustering and the observed trends in all of the isotopic ratio plots are consistent with a similar mantle source, although the overlap with several regional data arrays may not require a truly unique source.A second, smaller cluster of samples from the southern end of the Line Islands (purple squares) and another Necker Ridge sample (yellow diamond) exhibit elevated 87Sr/86Sr at a given 206Pb/204Pb ratio. These samples fall within the Marquesas compositional cloud, which trends toward higher 87Sr/86Sr. This signature is consistent with our tectonic/volcanic reconstruction model for the southern end of the Line Islands Ridge, which suggests influence of the Marquesas hotspot in this region at ca. 30–10 Ma. The cause of the offset of the Necker Ridge sample is uncertain but may be related to the Marquesas hotspot passing Necker Ridge at ca. 80 Ma.The isotope ratios of the samples along the Pukapuka Ridge suggest possible mixing between the Larson melt region (yellow star) and depleted mid-oceanic ridge basalt (MORB) mantle (DMM), with samples reflecting a greater contribution from DMM toward the east (white stars). This is consistent with our location of the Larson melt region in the vicinity and a lithosphere extension origin.We propose a new multiple-hotspots model to explain the complex Line Islands system. Our model includes three previously suggested hotspots (Crough, Marquesas, Tahiti), as well as the new proposed Larson melt region in the area of 125°W–129°W and 16°S–22°S. This new model not only addresses the eruption history of the Line Islands system, but it also may account for portions of the Mid-Pacific Mountains and the Pukapuka Ridge. Not all characteristics of this complex region are readily explained by mantle plumes alone, and alternative tectonic and magmatic processes may also be required. Overall, our study demonstrates the merits of a mantle plume model to explain the origins of the Line Islands system. Perhaps most importantly, our model provides predictive consequences for future tests with additional age dating and geochemical analyses along poorly constrained sections of the Line Islands system.We thank Dan Scheirer, Chris Kincaid, Victoria Fulfer, Kevin Konrad, and Yang Shen for helpful discussions. We also appreciate very useful reviews from Sabin Zahirovic, Kevin Konrad, and James Natland. This research was partially funded by the U.S. Geological Survey (grant G13AC00351) and the U.S. National Science Foundation (grant OCE-1158994). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

中文翻译：

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莱恩群岛（太平洋）的多熔源成因

太平洋中部的莱恩群岛火山链表现出许多热点生成海山链的特征；然而，缺乏可预测的年龄进展阻碍了之前关于此特征起源的模型。我们将板块构造重建与海山年龄日期和可用地球化学相结合，开发了一个新模型，该模型涉及多个熔体区域和多种熔体输送方式，以解释线岛系统的时空历史。我们的模型确定了一个新的熔体源区（Larson 熔体区在~17°S，~125°W），它促成了莱恩群岛、中太平洋山脉和可能的普卡普卡海脊的形成。莱恩群岛链是位于太平洋中部的海山和火山脊的集合，沿其 4500 公里长总体呈西北-东南走向（图 1；补充材料中的图 S1）。莱恩群岛的喷发年龄一般在 88 到 50 马之间；然而，沿火山链没有明显的年龄进展（Clague 和 Jarrard，1973；Winterer，1973；Jackson 和 Schlanger，1976；Lanphere 和 Dalrymple，1976a，1976b；Schlanger 等，1976；Saito 和 Ozima，1977； Haggerty 等人，1982 年；Davis 等人，2002 年。以前试图用单个热点轨迹（例如 Morgan，1972 年）解释线岛起源的尝试无法解释复杂的年龄分布，因此具有提出了多个热点（例如，Crough 和 Jarrard，1981；Duncan 和 Clague，1985）。替代模型包括泄漏转换断层（例如，Orwig 和 Kroenke，1980 年；Farrar 和 Dixon，1981 年）或与板块冷却相关的岩石圈张拉裂缝或为次岩石圈熔体在海底喷发提供路径的不同远场应力（例如，Natland 和 Winterer，2005 年）。最近的解释还表明，单个或多个热点模型都不能解释线岛的起源（Davis 等，2002）。取而代之的是，岩石圈扩散区域内异质地幔的融化被认为导致了复杂的喷发历史。 . 我们的模型使用更新的板块运动模型（Matthews 等人，2016 年）和年代久远的海山汇编（Clouard 和 Bonneville，2005 年；海山目录主页，https://earthref.org/SC/[2019 年 8 月访问]）以限制莱恩群岛的空间和时间喷发历史系统。我们还审查了同位素地球化学数据，以验证我们的解释与现有信息一致。我们的研究主要是对线岛系统起源地幔柱模型的测试，但我们承认，这个复杂区域的某些特征不能仅仅由地幔柱轻易解释，可能需要替代的构造和岩浆过程。 Line Islands 火山链沿其长度变化很大（图 1A；图 S1）。最北端的地区，我们称之为北火山省，是分布在 900 × 1500 公里区域的单个海山和东西向海山链的集合，位于中太平洋山脉紧邻东南部，包括约翰斯顿环礁。该链的中心区域由 1200 公里长和 200 公里宽的火山线群岛岭界定。Line Islands Ridge 的北端是一个圆形高原，包括金曼礁和巴尔米拉环礁，而南端包括范宁岛和圣诞岛。继续向南，Boudeuse Ridge 是一条 1200 公里长的线性海山链，由紧密间隔的海山组成，形成了 Line Islands 系统的南段。沿线群岛系统长度的火山作用年龄从 91 到 24 Ma，大多数年代久远的海山（27 个中的 23 个）的年龄在 86 到 55 Ma（表 S2）之间，并且沿着火山链没有明显的年龄进展（图 1B）。位于 Line Islands 两端的另外两个火山特征是西北部的中太平洋山脉和东南部的普卡普卡山脊（图 1A；图 S1）。中太平洋山脉是一片广阔的火山高原，绵延 2000 多公里，大致呈东西走向，位于夏威夷海脊西南。中太平洋山脉西半部平面大体等维（1200×1200km），年代为128～88Ma，东半部更细长（800×150km），呈西南—东北方向，一次喷发年龄日期为约。73 马。在最东端，有一系列狭窄的脊，走向西南-东北，其中包括内克尔脊，喷发年龄从 88 到 82 Ma。位于南端的普卡普卡海岭是一系列不连续的火山脊，呈东西走向，在土阿莫土群岛（向西）和拉诺拉希海山（向东）之间跨越 2500 公里。普卡普卡山脊沿线的火山活动显示出从大约 11 马在西端到约。6 Ma 在东太平洋海隆附近的东端（Sandwell 等人，1995 年）。我们使用了 GPlates 构造重建软件（Müller 等人，2016 年；https://www.gplates.org/）并包括旋转极点（ Matthews 等人，2016 年），太平洋板块上的热点位置（表 S1；Courtillot 等人，2003 年；Morgan 和 Morgan，2007 年），以及中太平洋海山年代的汇编（表 S2；Clouard 和 Bonneville，2005 年；海山目录主页）以模拟莱恩群岛的火山演化（图 1 和 2）。我们使用具有一系列反复试验热点位置的定性正向建模方法来获得视觉最佳拟合模型。可能还有莱恩群岛的南端（图 1B）。然而，Crough 热点轨迹对北部火山省和 Line Islands Ridge 的北半部的预测并不好，虽然它们离 Marquesas 热点轨迹最近，但它们仍然相距很远（~500 公里）。此外，这个最初的重建没有考虑沿线群岛海脊和北部火山省的海山年龄的混合。我们首选的重建需要一个额外的熔源区，目前位于 16°S、129°W 和 22°S 之间的弧线上， 124°W（图 1C），我们将其称为 Larson 熔融区，以纪念 Roger Larson 对揭示太平洋盆地复杂构造历史的重要贡献（Pockalny 等人，2015 年；Fletcher 等人，2020 年）。这个新热点位于靠近普卡普卡山脊东部边界的克劳夫和马克萨斯热点之间。构造重建沿着莱恩群岛山脊、穿过北部火山省的中心和中太平洋山脉追踪一条路径（参见补充材料中的视频 S1-S4）。Larson 融化区的时空历史与沿线群岛系统的大部分火山活动以及相邻的中太平洋山脉和 Pukapuka 海脊一致（图 1C、2 和 3）。克劳热点似乎与莱恩群岛的南端重合，而马克萨斯和塔希提岛的热点可能与莱恩群岛北端的部分重合，但程度大大减少（图 1B）。在情景（图 2 和图 3）中，中太平洋西部山脉是通过与 Larson 融化区的羽脊相互作用在 130-110 Ma 形成的。此时的融化区域很可能是位于太平洋-法拉隆扩张轴 500 公里范围内的强烈融化事件（即羽流头）（例如，Thiede 等人，1981 年；Fletcher 等人，2020 年）。中太平洋山脉的东部似乎比西部更年轻，并覆盖了莫洛凯断裂带前体的推断痕迹。中太平洋山脉的后期分布火山活动可能是由于大溪地热点从 110 到 85 Ma.Necker Ridge 的通过以及中太平洋山脉东端相关的东北向窄火山脊（图 1-3；图 S1）可能是离轴伸展喷发事件的结果，该喷发事件与约 95 Ma 或 Marquesas 热点在 85-75 Ma。根据我们的模型，线岛本身很可能是 Larson、Crough 和 Marquesas 热点的综合结果（图 2 和 3）。北部火山省似乎是由与 100 至 75 Ma 的 Larson 融化区以及可能是 75 至 65 Ma 的马克萨斯热点相关的分布火山活动造成的。Line Islands Ridge 的北半部在 80~65 Ma 期间与 Larson 熔融区的通道重合，而南半部在 100~85 Ma 期间与 Crough 热点和 Larson 熔融区在 70~50 Ma 期间重合。从 Line Islands Ridge 东侧发出的横纹脊表明存在伸展环境（Davis et al., 2002），但我们将热点轨迹和 Line Islands 的相似趋势解释为熔体导管热点轨迹（例如，摩根，1972 年）。克鲁夫热点的轨迹与 75 至 45 Ma 的布德斯海脊重合，也表明了熔体导管熔体输送方式。在莱恩群岛的南端之外，克拉夫热点在 50 到 20 Ma 期间与土阿莫土群岛重合，并与连接土阿莫土群岛和复活节微板块的一系列海山平行（图 2 和图 3）。有限的海山年龄信息无法提供足够的信息来评估熔体输送方式，因此这些特征可能是由于熔体导管或岩石圈延伸造成的。然而，Pukapuka Ridge 很可能是岩石圈伸展的结果，Larson 熔融区可能是一个熔融源（Sandwell 等，1995；Lynch，1999；Janney 等，2000）。我们提出了四种不同的熔融源（例如，Crough、Marquesas、Tahiti 和 Larson 热点）来解释 Line Islands 以及邻近的中太平洋山脉和 Pukapuka Ridge（图 2 和图 3；图 S2）的形成。Larson 和Crough 热点是火山活动的主要贡献者，但这些熔体来源都没有一直列在深部地幔柱或热点目录中（例如，Courtillot 等人，2003 年；Montelli 等人，2006 年）。然而，剪切波速度模型（French 和 Romanowicz，2015）表明，这两个热点可能都与地幔柱源有关（图 4）。拉尔森和附近的皮特凯恩热点与广阔的南太平洋超级膨胀区的深地幔柱源有关。克劳夫和可能的复活节热点与复活节微板块附近的中地幔柱源有关。根据横波速度模型，马克萨斯热点似乎也与中地幔羽流源相连，而塔希提岛热点似乎有一个浅地幔源。提出了几种熔体输送过程来解释沿线群岛系统观察到的各种火山形态（图 3）。我们提出的中太平洋山脉羽状脊起源、布德斯海岭熔体导管起源和普卡普卡海岭岩石圈伸展起源与先前的解释一致（Winterer 和 Metzler，1984；Lynch，1999；Davis 等., 2002)。Line Islands Ridge 的熔体输送方式最近归因于扩散的岩石圈伸展和随后的火山作用（Davis 等，2002）；然而，火山链相对于相交断裂带的大喷发体积和正交方向与其他提议的伸展火山脊（例如，普卡普卡海岭）有显着不同。我们相信 Line Islands Ridge 的时空历史可以通过重叠 Crough 热点和 Larson 融化区的常规热点轨迹来更好地解释。北部火山省以前也被归因于岩石圈伸展，以解释该地区的横纹海山链（例如，克里岭）（Natland，1976 年）。我们相信这种机制仍然是一个可行的起源，但我们也建议分布式火山起源来解释分散的海山。在我们的解释中，横纹海山分布火山作用的熔体源很小，与拉森熔体区和/或马克萨斯热点的通过有关的残余地幔非均质性。来自 Line Islands 系统沿线的海山和海脊以及相关火山特征的有限地球化学数据为其可能的起源提供了额外的限制和线索（图 S2；表 S3）。这在 87Sr/86Sr 与 206Pb/204Pb 的图中得到了最好的展示，其中大部分样本来自北部火山省和 Line Islands Ridge 北部部分（黄色三角形）（Garcia 等人，1993 年；Konter 等人，1993 年）。 , 2008) 聚集在一起并与来自 Boudeuse Ridge（蓝色倒三角形）的样本（Garcia 等人，1993 年）、来自 Necker Ridge 的一个样本（黄色菱形）（Garcia 等人，1993 年）和一个样本重合在 Pukapuka Ridge（黄星）的西端（Janney 等，2000）。所有同位素比率图中的这种聚类和观察到的趋势与类似的地幔源一致，尽管与几个区域数据阵列的重叠可能不需要真正独特的来源。 来自莱恩岛南端（紫色方块）和另一个内克尔岭样本（黄色菱形）的第二个较小的样本群在 87Sr/86Sr给定的 206Pb/204Pb 比率。这些样品属于 Marquesas 成分云，趋向于更高的 87Sr/86Sr。这个特征与我们的 Line Islands Ridge 南端的构造/火山重建模型一致，这表明该地区的 Marquesas 热点在大约 30-10 毫安。内克尔岭样本偏移的原因尚不确定，但可能与马克萨斯热点在约 80 马。普卡普卡海岭沿线样品的同位素比率表明 Larson 熔融区（黄色星）和大洋中脊玄武岩（MORB）地幔枯竭（DMM）之间可能存在混合，样品反映 DMM 向东（白色）的贡献更大星星）。这与我们在附近的 Larson 熔融区的位置和岩石圈延伸起源一致。我们提出了一个新的多热点模型来解释复杂的线岛系统。我们的模型包括三个先前建议的热点（Crough、Marquesas、Tahiti），以及在 125°W–129°W 和 16°S–22°S 区域内新提出的 Larson 熔化区。这个新模型不仅解决了莱恩群岛系统的喷发历史，而且还可能解释了中太平洋山脉和普卡普卡山脊的部分地区。并非这个复杂区域的所有特征都可以单独用地幔柱来解释，而且可能还需要其他构造和岩浆过程。总的来说，我们的研究证明了地幔柱模型在解释线岛系统起源方面的优点。也许最重要的是，我们的模型为未来的测试提供了预测结果，沿着 Line Islands 系统的约束较差的部分进行了额外的年龄定年和地球化学分析。我们感谢 Dan Scheirer、Chris Kincaid、Victoria Fulfer、Kevin Konrad 和 Yang Shen 的有益讨论。我们还感谢 Sabin Zahirovic、Kevin Konrad 和 James Natland 提供的非常有用的评论。这项研究由美国地质调查局（G13AC00351）和美国国家科学基金会（OCE-1158994）部分资助。任何使用贸易、公司、